Ive been sitting here worried the lid blew out! Glad you got it home. Its about as rough as I expected, but that lid looks great. It will cook as-is, but you won't get the full experience of the weber without being able to control your air flow.
I used star nuts from the bicycle shop, I had to use 1 and 1/8 inch ones, and used a grinder to make them somewhat square. Then screwed the bolt in a little and tapped it in slowly and tried to keep it straight. You can just tap the side of the bolt to straighten it out if it starts getting out of control. Went pretty easy for me but I may have gotten lucky.
I know @red5wrangler used stainless all thread through the pipe, with washers that are the size of the inside diameter of the tubing to keep it lined up. I probably would have done that, but I already sourced the star nuts and it worked well, but I haven't found stainless bolts in the metric thread that are long enough.